In recent years, methods intended for a thermal power plant or the like that uses a lot of fossil fuel have been studied, i.e., a method for separating and recovering carbon dioxide from exhaust combustion gas by bringing the exhaust combustion gas into contact with amine absorbing liquid and a method for storing the recovered carbon dioxide without releasing the carbon dioxide into the air.
Specifically, a carbon dioxide recovery apparatus including an absorber and a regenerator is known. The absorber makes the amine absorbing liquid absorb the carbon dioxide contained in the exhaust combustion gas. After the absorbing liquid that has absorbed the carbon dioxide (rich liquid) is supplied from the absorber to the regenerator, the regenerator heats the rich liquid to release the carbon dioxide gas from the rich liquid, thereby regenerating the absorbing liquid (for example, refer to Patent Document 1).
The exhaust combustion gas contains oxygen and sulfur dioxide, which are absorbed together with the carbon dioxide into the absorbing liquid at the absorber. There is a problem in that the absorbing liquid that has absorbed the oxygen and the sulfur dioxide is deteriorated, and the performance of carbon dioxide absorption thereof is decreased.    Patent Document 1: Japanese Patent Application Laid-Open No. 2004-323339